Multilayer capacitor and manufacturing method for same

ABSTRACT

A manufacturing method for a multilayer capacitor includes alternately laminating dielectric layers and conductor layers including less than 50 included in a first arrangement and a second arrangement different from the first arrangement when viewed from a lamination direction to form a laminate in which at least one pair of the conductor layers adjacent to each other with the dielectric layer interposed therebetween are included in the first or second arrangement, pressing the laminate to stretch the conductor layers in a direction perpendicular or substantially perpendicular to the lamination direction, pressing the laminate to bend the conductor layers in the lamination direction, and forming first and second outer electrodes on laminate surfaces such that the first outer electrode is connected to the conductor layers included in the first arrangement and the second outer electrode is connected to the conductor layers included in the second arrangement.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a multilayer capacitor and amanufacturing method for a multilayer capacitor. More particularly, thepresent invention relates to an ultra-small multilayer capacitor and amanufacturing method for an ultra-small multilayer capacitor.

2. Description of the Related Art

Japanese Unexamined Patent Application Publication No. 2007-299984discloses a multilayer capacitor that is intended to reduce variationsof an electrostatic capacitance. Generally, a multilayer capacitor isdesigned to have the desired electrostatic capacitance. Parametersdetermining the electrostatic capacitance of the multilayer capacitorinclude the dielectric constant of a dielectric that constitutes ceramiclayers, i.e., effective dielectric layers, the area of a region where apair of electrodes is opposed to each other with the ceramic layerssandwiched therebetween, the distance between the electrodes, and thenumber of the laminated ceramic layers. The electrostatic capacitance ofthe multilayer capacitor is proportional to the dielectric constant ofthe dielectric, the area of the region where the pair of electrodes isopposed to each other, and the number of the laminated ceramic layers,whereas it is reversely proportional to the distance between theelectrodes. In designing the multilayer capacitor having the desiredelectrostatic capacitance, it has so far been usual to employ one of thefollowing three adjustment methods.

In a first adjustment method, the number of the laminated ceramic layersis increased or decreased. In a second adjustment method, the distancebetween the electrodes is increased or decreased by changing thethickness of the ceramic layer. In a third adjustment method, the areaof the region where the pair of electrodes is opposed to each other isincreased or decreased by shifting the arranged positions of the pair ofelectrodes.

In the case of a multilayer capacitor downsized to an ultra-small size,the number of the laminated ceramic layers is reduced. Therefore, achange rate of the electrostatic capacitance caused by increasing ordecreasing the number of the laminated ceramic layers is increasedrelatively. In more detail, when the number of the laminated ceramiclayers is 200, the electrostatic capacitance per ceramic layer occupiesjust 0.5% of that of the entire multilayer capacitor, and theelectrostatic capacitance can be adjusted in units of 0.5%. However,when the number of the laminated ceramic layers is 50, the electrostaticcapacitance per ceramic layer occupies 2% of that of the entiremultilayer capacitor, and when the number of the laminated ceramiclayers is 10, the electrostatic capacitance per ceramic layer occupies10% of that of the entire multilayer capacitor.

Thus, as the number of the laminated ceramic layers is reduced, theelectrostatic capacitance of the multilayer capacitor is changed to alarger extent depending on an increase or a decrease in the number ofthe laminated ceramic layers. It is therefore difficult, in theultra-small multilayer capacitor, to obtain the desired electrostaticcapacitance by the adjustment method of increasing or decreasing thenumber of the laminated ceramic layers.

When a proportion of the electrostatic capacitance per ceramic layerwith respect to that of the entire multilayer capacitor is large, theelectrostatic capacitance of the multilayer capacitor is greatly changeddepending on an increase or a decrease in the distance between theelectrodes. In the ultra-small multilayer capacitor, therefore, it isalso difficult to obtain the desired electrostatic capacitance by theadjustment method of increasing or decreasing the distance between theelectrodes.

Moreover, in the multilayer capacitor downsized to the ultra-small size,a space usable to shift the positions of the pair of electrodes relativeto each other is reduced from the viewpoint of ensuring moistureresistance, etc., and a difficulty occurs in shifting the positions ofthe pair of electrodes to increase or decrease the area of the regionwhere the pair of electrodes is opposed to each other. Accordingly, itis difficult, in the ultra-small multilayer capacitor, to obtain thedesired electrostatic capacitance by the adjustment method of shiftingthe positions of the pair of electrodes, thereby increasing ordecreasing the area of the region where the pair of electrodes isopposed to each other.

Thus, the ultra-small multilayer capacitor has a difficulty in obtainingthe desired electrostatic capacitance by the ordinary adjustmentmethods.

SUMMARY OF THE INVENTION

In view of the problems described above, preferred embodiments of thepresent invention provide an ultra-small multilayer capacitor having adesired electrostatic capacitance, and a manufacturing method for anultra-small multilayer capacitor.

According to one preferred embodiment of the present invention, there isprovided a manufacturing method for a multilayer capacitor including alaminate that includes conductor layers and dielectric layersalternately laminated, and that has external dimensions with a length ofabout 0.45 mm or less and a width of about 0.25 mm or less when viewedfrom a lamination direction, for example, and a first outer electrodeand a second outer electrode disposed on surfaces of the laminate.

The manufacturing method includes a laminating step of alternatelylaminating the dielectric layers and the conductor layers such that theconductor layers are in a first arrangement and a second arrangement,the second arrangement being different from the first arrangement whenviewed from the lamination direction, and such that less than 50 of theconductor layers are included in the first arrangement or the secondarrangement, to form a laminate in which at least one pair of theconductor layers adjacent to each other with the dielectric layerinterposed therebetween are both included in the first arrangement orboth included in the second arrangement, a stretching step of pressingthe laminate to stretch the conductor layers in a directionperpendicular or substantially perpendicular to the laminationdirection, a bending step of pressing the laminate to bend the conductorlayers in the lamination direction, and an outer electrode forming stepof forming the first outer electrode and the second outer electrode onthe surfaces of the laminate in a state where the first outer electrodeis connected to ones of the conductor layers included in the firstarrangement, and the second outer electrode is connected to others ofthe conductor layers included in the second arrangement.

In a specific preferred embodiment of the present invention, preferably,an effective dielectric layer is defined such that one of the dielectriclayers is sandwiched between the conductor layer included in the firstarrangement and the conductor layer included in the second arrangement;an ineffective dielectric layer is defined such that one of thedielectric layers is sandwiched between the conductor layers bothincluded in one of the first arrangement and the second arrangement; andin the laminating step the conductor layers and the dielectric layersare laminated to satisfy the total number of the effective dielectriclayers and the total number of the conductor layers which are determinedbased on electrostatic capacitance per the effective dielectric layerand an increase rate of electrostatic capacitance of the multilayercapacitor due to an increase of one ineffective dielectric layer.

In a specific preferred embodiment of the present invention, preferably,the conductor layers and the dielectric layers are laminated in thelaminating step such that at least one of the two conductor layerspositioned at both ends of the laminate in the lamination direction isadjacent to the ineffective dielectric layer.

In a specific preferred embodiment of the present invention, preferably,the conductor layers and the dielectric layers are laminated in thelaminating step such that at least one of the conductor layers isadjacent to the ineffective dielectric layer, the at least one of theconductor layers being positioned in a central region resulting fromdividing a space between the two conductor layers positioned at bothends of the laminate in the lamination direction into three equalregions.

According to another preferred embodiment of the present invention,there is provided a multilayer capacitor including a laminate thatincludes conductor layers and dielectric layers alternately laminated,and that has external dimensions with a length of about 0.45 mm or lessand a width of about 0.25 mm or less when viewed from a laminationdirection, and a first outer electrode and a second outer electrodedisposed on surfaces of the laminate, which are spaced from each otherin a lengthwise direction of the laminate. In the laminate, thedielectric layers and the conductor layers are alternately laminatedsuch that the conductor layers are arranged in a first arrangement and asecond arrangement, the second arrangement being different from thefirst arrangement when viewed from the lamination direction, and suchthat 50 of the conductor layers are included in the first arrangement orthe second arrangement. The first outer electrode is connected to onesof the conductor layers included in the first arrangement. The secondouter electrode is connected to others of the conductor layers includedin the second arrangement. A width of each conductor layer has adifference of less than about 0.12 mm between the width of the conductorlayer and a width of the laminate, and is about 70% or less of the widthof the laminate, for example. At least one of the dielectric layers isan ineffective dielectric layer that is sandwiched between the conductorlayers both positioned in one of the first arrangement and the secondarrangement. At least one of the dielectric layers is an effectivedielectric layer that is sandwiched between the conductor layer includedin the first arrangement and the conductor layer included in the secondarrangement. At least one of the conductor layers adjacent to theeffective dielectric layer is curved in the lamination direction.

In a specific preferred embodiment of the present invention, preferably,an extent of curvature of at least one of the two conductor layerspositioned at both ends of the laminate in the lamination direction, theextent of curvature being measured in a section perpendicular orsubstantially perpendicular to the lengthwise direction, is larger thana thickness of the dielectric layer that is adjacent to the at least oneof the two conductor layers.

In a specific preferred embodiment of the present invention, preferably,at least one of the two conductor layers positioned at both ends of thelaminate in the lamination direction is adjacent to the ineffectivedielectric layer.

In a specific preferred embodiment of the present invention, preferably,at least one of the conductor layers is adjacent to the ineffectivedielectric layer, the at least one of the conductor layers beingpositioned in a central region resulting from dividing a space betweenthe two conductor layers positioned at both ends of the laminate in thelamination direction into three equal regions.

According to various preferred embodiments of the present invention,ultra-small multilayer capacitors having the desired electrostaticcapacitance are provided.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an external appearance of amultilayer capacitor according to a first preferred embodiment of thepresent invention.

FIG. 2 is a sectional view of the multilayer capacitor illustrated inFIG. 1 when taken along a line II-II and viewed from a direction denotedby arrow.

FIG. 3 is a sectional view of the multilayer capacitor illustrated inFIG. 1 when taken along a line III-III and viewed from a directiondenoted by arrow.

FIG. 4 is a sectional view of the multilayer capacitor illustrated inFIG. 2 when taken along a line IV-IV and viewed from a direction denotedby arrow.

FIG. 5 is a sectional view of the multilayer capacitor illustrated inFIG. 2 when taken along a line V-V and viewed from a direction denotedby arrow.

FIG. 6 is a flowchart representing a manufacturing method for themultilayer capacitor according to the first preferred embodiment of thepresent invention.

FIG. 7 is a sectional view of the multilayer capacitor, taken along alengthwise direction L thereof, the view illustrating a mother laminatebefore being pressed.

FIG. 8 is a sectional view of the multilayer capacitor, taken along awidthwise direction W thereof, the view illustrating the mother laminatebefore being pressed.

FIG. 9 is a sectional view of the multilayer capacitor, taken along thelengthwise direction L thereof, the view illustrating the motherlaminate after being pressed.

FIG. 10 is a sectional view of the multilayer capacitor, taken along thewidthwise direction W thereof, the view illustrating the mother laminateafter being pressed.

FIG. 11 is a graph depicting a relation between the number of laminatedineffective dielectric layers and electrostatic capacitance of themultilayer capacitor.

FIG. 12 is a graph depicting a relation between the number of laminatedineffective dielectric layers and an apparent effective area of aconductor layer.

FIG. 13 is a flowchart representing the manufacturing method for themultilayer capacitor according to the first preferred embodiment of thepresent invention.

FIG. 14 is a sectional view illustrating a structure of a multilayercapacitor according to a second preferred embodiment of the presentinvention.

FIG. 15 is a sectional view of the multilayer capacitor according to thesecond preferred embodiment of the present invention, taken along alengthwise direction L thereof, the view illustrating a mother laminatebefore being pressed.

FIG. 16 is a sectional view of the multilayer capacitor according to thesecond preferred embodiment of the present invention, taken along thelengthwise direction L thereof, the view illustrating the motherlaminate after being pressed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Multilayer capacitors according to preferred embodiments of the presentinvention and manufacturing methods for the multilayer capacitors willbe described below with reference to the drawings. In the followingdescription of the preferred embodiments, the same or correspondingelements and portions in the drawings are denoted by the same referencesings, and explanation of those elements or portions is not repeated.

First Preferred Embodiment

FIG. 1 is a perspective view illustrating an external appearance of amultilayer capacitor according to a first preferred embodiment of thepresent invention. FIG. 2 is a sectional view of the multilayercapacitor illustrated in FIG. 1 when taken along a line II-II and viewedfrom a direction denoted by arrow. FIG. 3 is a sectional view of themultilayer capacitor illustrated in FIG. 1 when taken along a lineIII-III and viewed from a direction denoted by arrow. FIG. 4 is asectional view of the multilayer capacitor illustrated in FIG. 2 whentaken along a line IV-IV and viewed from a direction denoted by arrow.FIG. 5 is a sectional view of the multilayer capacitor illustrated inFIG. 2 when taken along a line V-V and viewed from a direction denotedby arrow. Definition of directions used in the following description,i.e., a lengthwise direction L of a laminate, a widthwise direction W ofthe laminate, and a thickness direction T of the laminate, are as perillustrated in FIG. 1.

As illustrated in FIGS. 1 to 5, a multilayer capacitor 100 according tothe first preferred embodiment of the present invention includes alaminate 110 that includes dielectric layers 130 and conductor layers140 alternately laminated, and that includes a first principal surface111 and a second principal surface 112 positioned at the opposite sides,and a pair of outer electrodes 120 including a first outer electrode 121and a second outer electrode 122 disposed on surfaces of the laminate110.

A direction in which the dielectric layers 130 and the conductor layers140 are laminated is perpendicular or substantially perpendicular toboth the lengthwise direction L of the laminate 110 and the widthwisedirection W of the laminate 110. In other words, the direction in whichthe dielectric layers 130 and the conductor layers 140 are laminated isparallel or substantially parallel to the thickness direction T of thelaminate 110.

The laminate 110 further includes a first end surface 115 and a secondend surface 116 interconnecting the first principal surface 111 and thesecond principal surface 112 and positioned opposite to each other, anda first lateral surface 113 and a second lateral surface 114interconnecting the first principal surface 111 and the second principalsurface 112, interconnecting the first end surface 115 and the secondend surface 116, and positioned opposite to each other. The shortestdistance between the first lateral surface 113 and the second lateralsurface 114 is less than that between the first end surface 115 and thesecond end surface 116. In other words, the size of the laminate 110 inthe widthwise direction W is smaller than that of the laminate 110 inthe lengthwise direction L. Alternatively, the size of the laminate 110in the widthwise direction W of the laminate 110 may be larger than thatof the laminate 110 in the lengthwise direction L. The laminate 110preferably has a substantially rectangular parallelepiped externalshape. The concept of “substantially rectangular parallelepiped externalshape” involves a shape resulting from rounding corners and/or ridges ofa rectangular parallelepiped.

The laminate 110 preferably has external dimensions with a length ofabout 0.45 mm or less and a width of about 0.25 mm or less when viewedfrom the lamination direction, for example. In this preferredembodiment, the external dimensions (design values) of the laminate 110preferably are about 0.212 mm in length and about 0.102 mm in width, forexample.

In this preferred embodiment, the pair of outer electrodes 120 isdisposed on the surfaces of the laminate 110 at positions spaced fromeach other in the lengthwise direction L of the laminate 110. Morespecifically, the pair of outer electrodes 120 includes a first outerelectrode 121 disposed at the side including the first end surface 115in the lengthwise direction L of the laminate 110, and a second outerelectrode 122 disposed at the side including the second end surface 116in the lengthwise direction L of the laminate 110.

In the laminate 110, the conductor layers 140 and the dielectric layers130 are alternately laminated in a state where the conductor layers arearranged to be positioned in a first arrangement and a secondarrangement, the second arrangement being different from the firstarrangement when viewed from the lamination direction, such that theconductor layers in number less than 50 are each included in the firstarrangement or the second arrangement. The conductor layers 140 includea plurality of first conductor layers 141, which are included in thefirst arrangement and are connected to the first outer electrode 121,and a plurality of second conductor layers 142, which are included inthe second arrangement and are connected to the second outer electrode122.

The first conductor layers 141 and the second conductor layers 142 areeach preferably substantially rectangular when looked at in a plan view.In more detail, three sides of each first conductor layer 141 except fora side positioned at the first end surface 115 are expanded outwardswhen looked at in a plan view. Three sides of each second conductorlayer 142 except for a side positioned at the second end surface 116 areexpanded outwards when looked at in a plan view.

In this preferred embodiment, the plurality of first conductor layers141 is exposed to the first end surface 115 of the laminate 110, and isconnected to the first outer electrode 121 at the first end surface 115.The plurality of second conductor layers 142 is exposed to the secondend surface 116 of the laminate 110, and is connected to the secondouter electrode 122 at the second end surface 116. In this preferredembodiment, the number of the laminated first conductor layers 141 is 6,and the number of the laminated second conductor layers 142 is 7. Thus,the number of the laminated conductor layers 140 is 13.

The width of the conductor layer 140 is set such that the differencebetween the width of the conductor layer 140 the width of the laminate110 preferably is less than about 0.12 mm, and that it is about 70% orless of the width of the laminate 110, for example. As a result,later-described adjustment of the electrostatic capacitance of themultilayer capacitor 100 is facilitated. In this preferred embodiment,the width (design value) of the conductor layer 140 preferably is about0.047 mm, for example. Accordingly, the difference between the width(design value) of the conductor layer 140 and the width (design value)of the laminate 110 preferably is about 0.055 mm, and the width (designvalue) of the conductor layer 140 is about 46% of the width (designvalue) of the laminate 110, for example.

The dielectric layers 130 include a first outer layer portion 131defining the first principal surface 111, a second outer layer portion132 defining the second principal surface 112, at least one effectivedielectric layer 133 sandwiched between the first conductor layer 141and the second conductor layer 142, and at least one ineffectivedielectric layer sandwiched between the first conductor layers 141 orbetween the second conductor layers 142. The ineffective dielectriclayer includes a first ineffective dielectric layer 134 sandwichedbetween the first conductor layers 141 and a second ineffectivedielectric layer 135 sandwiched between the second conductor layers 142.

The thickness of the ineffective dielectric layer is equal orsubstantially equal to that of the effective dielectric layer 133. Morespecifically, the thickness of the ineffective dielectric layer is morethan about 0.5 time and less than about 2 times that of the effectivedielectric layer 133, for example. The ineffective dielectric layer andthe effective dielectric layer 133 are defined by ceramic green sheetshaving the same thickness, as described later.

The conductor layers 140 include a conductor layer 140 sandwichedbetween the effective dielectric layer 133 and the ineffectivedielectric layer. More specifically, between the first conductor layer141 and the second conductor layer 142, another first conductor layer141 or another second conductor layer 142 is laminated with thedielectric layer 130 sandwiched between the adjacent conductor layers.

A region of the laminate 110, which is sandwiched between the firstouter layer portion 131 and the second outer layer portion 132, iscalled an inner layer portion. In this preferred embodiment, the innerlayer portion includes nine effective dielectric layers 133, one firstineffective dielectric layer 134, and two second ineffective dielectriclayers 135.

The first ineffective dielectric layer 134 is positioned at an end ofthe inner layer portion on the side close to the second principalsurface 112. One of the two second ineffective dielectric layers 135 ispositioned at an end of the inner layer portion on the side close to thefirst principal surface 111. In other words, two conductor layers 140positioned at both the ends of the laminate 110 in the laminationdirection are each adjacent to the ineffective dielectric layer. Morespecifically, a second conductor layer 148 positioned closest to thefirst principal surface 111 in the lamination direction of the laminate110 is adjacent to the second ineffective dielectric layer 135. A firstconductor layer 149 positioned closest to the second principal surface112 in the lamination direction of the laminate 110 is adjacent to thefirst ineffective dielectric layer 134.

The other of the two second ineffective dielectric layers 135 ispositioned in the central region resulting from dividing the spacebetween two conductor layers 140, which are positioned at both the endsof the laminate 110 in the lamination direction, into the three equalregions, and it is located nearest to the center of the inner layerportion. Stated in another way, one conductor layer 140 positioned inthe central region resulting from dividing the space between the twoconductor layers 140, which are positioned at both the ends of thelaminate 110 in the lamination direction, into the three equal regionsis adjacent to the ineffective dielectric layer.

In the multilayer capacitor 100 according to this preferred embodiment,the conductor layer 140 adjacent to the effective dielectric layer 133is curved. More specifically, as illustrated in FIG. 2, the conductorlayer 140 adjacent to the effective dielectric layer 133 is curved in asection, which is perpendicular or substantially perpendicular to thewidthwise direction W of the laminate 110, to project in a directionaway from the center of the laminate 110 along the lamination direction.As illustrated in FIG. 3, the conductor layer 140 adjacent to theeffective dielectric layer 133 is further curved in a section, which isperpendicular or substantially perpendicular to the lengthwise directionL of the laminate 110, to project in a direction away from the center ofthe laminate 110 along the lamination direction.

An extent of curvature of the conductor layer 140 adjacent to thedielectric layer 130 increases as the position of the relevant conductorlayer 140 approaches the end of the laminate 110 in the laminationdirection. As illustrated in FIG. 3, an extent of curvature of each oftwo conductor layers 140 in the section perpendicular or substantiallyperpendicular to the lengthwise direction L of the laminate 110, thosetwo conductor layers 140 being positioned at both the ends of thelaminate 110 in the lamination direction, is larger than the thicknessof the ineffective dielectric layer that is adjacent to the relevantconductor layer 140. More specifically, an extent B₁ of curvature of thesecond conductor layer 148, which is positioned closest to the firstprincipal surface 111 of the laminate 110 in the lamination direction,is larger than the thickness of the second ineffective dielectric layer135 that is adjacent to the second conductor layer 148. An extent B₂ ofcurvature of the first conductor layer 149, which is positioned closestto the second principal surface 112 of the laminate 110 in thelamination direction, is larger than the thickness of the firstineffective dielectric layer 134 that is adjacent to the first conductorlayer 149.

In each of the two conductor layers 140 positioned at both the ends ofthe laminate 110 in the lamination direction, the extent of curvature inthe section perpendicular or substantially perpendicular to thelengthwise direction L of the laminate 110 is preferably larger thanthat in the section perpendicular or substantially perpendicular to thewidthwise direction W of the laminate 110.

Individual constituent elements of the multilayer capacitor 100 will bedescribed in detail below.

A material constituting the dielectric layer 130 may be a dielectricceramic containing, as a main component, BaTiO₃, CaTiO₃, SrTiO₃, CaZrO₃,or the like. The material constituting the dielectric layer 130 may be adielectric ceramic containing, in addition to the above-mentioned maincomponent, an accessory component such as a Mn compound, a Mg compound,a Si compound, a Co compound, a Ni compound, or a rare earth compound.

A material constituting the conductor layer 140 may be a metal such asNi, Cu, Ag, Pd or Au, or an alloy containing at least one of thosemetals, e.g., an alloy of Ag and Pd. The thickness of each conductorlayer 140 is preferably about 0.2 μm or more and about 2.0 μm or lessafter firing, for example.

Each of the pair of outer electrodes 120 includes an underlying layerthat is disposed in covering relation to both the end portions of thelaminate 110, and a plating layer that is disposed in covering relationto the underlying layer. A material constituting the underlying layermay be a metal such as Ni, Cu, Ag, Pd or Au, or an alloy containing atleast one of those metals, e.g., an alloy of Ag and Pd. The thickness ofthe underlying layer is preferably about 10.0 μm or more and about 50.0μm or less.

The underlying layer may be formed by coating conductive pastes overboth the end portions of the laminate 110 and baking the coated pastes,or formed through co-firing together with the conductor layers 140. Asan alternative, the underlying layer may be formed by plating coatingsover both the end portions of the laminate 110, or formed by coatingconductive resins, including thermosetting resin, over both the endportions of the laminate 110 and solidifying the coated resins.

A material constituting the plating layer may be a metal such as Ni, Cu,Ag, Pd or Au, or an alloy containing at least one of those metals, e.g.,an alloy of Ag and Pd.

The plating layer may be constituted by a plurality of layers. In thatcase, the plating layer is preferably of a two-layer structure includinga Ni plating layer and a Sn plating layer on the Ni plating. The Niplating layer defines and functions as a solder barrier layer. The Snplating layer exhibits good wettability with respect to solder. Thethickness of the plating layer per layer is preferably about 1.0 μm ormore and about 10.0 μm or less, for example.

A non-limiting example of a manufacturing method for the multilayercapacitor 100 according to this preferred embodiment will be describedbelow. FIG. 6 is a flowchart representing the manufacturing method forthe multilayer capacitor according to the first preferred embodiment ofthe present invention.

As illustrated in FIG. 6, when manufacturing the multilayer capacitor100, a ceramic slurry is first prepared (step S1). More specifically,ceramic powder, a binder, and a solvent are mixed at a predeterminedmixing ratio, such that the ceramic slurry is obtained.

Then, a ceramic green sheet is formed (step S2). More specifically, theceramic slurry is coated in a sheet shape over a carrier film byemploying, e.g., a die coater, a gravure coater, or a micro-gravurecoater, such that the ceramic green sheet is formed.

Then, mother sheets are formed (step S3). More specifically, in some ofthe plurality of ceramic green sheets formed described above, aconductive paste to form the conductor layer is coated over each of thesome ceramic green sheets in a predetermined pattern by a screenprinting method or a gravure printing method. As illustrated in FIG. 8described later, a conductor pattern 14 includes a circular arc shape inwhich the thickness of the conductor pattern 14 gradually decreases froma central portion toward an end portion of the conductor pattern 14 inthe widthwise direction.

Thus, the ceramic green sheets each including the conductive patternformed thereon and each becoming the conductor layer, and the ceramicgreen sheets each not including the conductive pattern formed thereonare prepared as the mother sheets. The conductive paste to form theconductor layers may contain other known binder and solvent.

Then, the mother sheets are laminated (step S4). More specifically, apredetermined number of the ceramic green sheets each not including theconductive pattern formed thereon are laminated to form the second outerlayer portion 132. On the outer layer portion 132, the plurality ofceramic green sheets each including the conductive pattern formedthereon are successively laminated to form the inner layer portion. Onthe inner layer portion, a predetermined number of the ceramic greensheets each not including the conductive pattern formed thereon arelaminated to form the first outer layer portion 131. As a result, amother laminate including the plurality of laminated mother sheets isconstituted.

Then, the mother laminate is pressed such that the conductor patternsbecoming the conductor layers are stretched (step S5) and curved (stepS6). While, in this preferred embodiment, the step S5 of stretching theconductor patterns becoming the conductor layers and the step S6 ofcurving the conductor patterns becoming the conductor layers areperformed at the same time, the present invention is not limited to suchan example, and the steps S5 and S6 may be performed separately. Inanother example, after performing the step S5 of stretching theconductor patterns becoming the conductor layers by pressing a motherlaminate that constitutes only the inner layer portion, the step S6 ofcurving the conductor patterns becoming the conductor layers may beperformed by laminating the predetermined number of ceramic greensheets, which constitute at least one of the first outer layer portion131 and the second outer layer portion 132, on the relevant motherlaminate, and by pressing it again.

FIG. 7 is a sectional view of the multilayer capacitor, taken along thelengthwise direction L thereof, the view illustrating the motherlaminate before being pressed. FIG. 8 is a sectional view of themultilayer capacitor, taken along the widthwise direction W thereof, theview illustrating the mother laminate before being pressed. FIG. 9 is asectional view of the multilayer capacitor, taken along the lengthwisedirection L thereof, the view illustrating the mother laminate afterbeing pressed. FIG. 10 is a sectional view of the multilayer capacitor,taken along the widthwise direction W thereof, the view illustrating themother laminate after being pressed.

As illustrated in FIG. 7, in a mother laminate 11, a region A where theconductor patterns 14 exist in a comparatively large number and a regionB where the conductor patterns 14 exist in a comparatively small numberare alternately present in the lengthwise direction L of the laminate110. On the other hand, as illustrated in FIG. 8, in the mother laminate11, the region A where the conductor patterns 14 exist in a large numberand a region C where the conductor patterns 14 do not exist and only adielectric portion 13 exists are alternately present in the widthwisedirection W of the laminate 110.

As illustrated in FIGS. 7 and 8, the mother laminate is pressed in thelamination direction for pressure bonding with a pair of flat-plate dies91. In the mother laminate 11, the density of the laminated conductorpatterns is higher in the region A than in the regions B and C.Therefore, the conductor patterns 14 positioned in the region A arepressed and stretched toward the regions B and C. The conductor patterns14 having been stretched toward the regions B and C are further pressedby the ceramic materials having flowed from the first outer layerportion or the second outer layer portion. Thus, the stretched conductorpatterns 14 are projected in a downward or upward convex shape. Asillustrated in FIGS. 7 and 8, the mother laminate 11 is preferablypressed in such a state that rubbers 92 are attached to pressingsurfaces of the pair of flat-plate dies 91. With the provision of therubbers 92, the conductor patterns 14 are caused to curve moreeffectively. As described above, the mother laminate is formed.

Here, in one of the laminates adjacent to each other in the lengthwisedirection of the laminate when the mother laminate is divided asdescribed later, the ceramic green sheets including the conductorpatterns formed to be included in the first arrangement and becoming thefirst conductor layers 141 are each called an A pattern, and the ceramicgreen sheets including the conductor patterns formed to be included inthe second arrangement and becoming the second conductor layers 142 areeach called a B pattern. By laminating the ceramic green sheets of the Apattern and the B pattern, the ceramic green sheet sandwiched betweenthe laminated conductor patterns becomes the effective dielectric layer133.

On the other hand, by laminating the ceramic green sheets of the Apattern, the ceramic green sheet sandwiched between the laminatedconductor patterns becomes the first ineffective dielectric layer 134.By laminating the ceramic green sheets of the B pattern, the ceramicgreen sheet sandwiched between the laminated conductor patterns becomesthe second ineffective dielectric layer 135.

Stated in another way, the effective dielectric layer 133, the firstineffective dielectric layer 134, and the second ineffective dielectriclayer 135 can be formed by preparing only two types of the ceramic greensheets, i.e., the A pattern and the B pattern, each including theconductor pattern formed thereon. Thus, the mother laminate 11 can bemanufactured easily and efficiently. Moreover, the A pattern and the Bpattern can be both prepared by using the ceramic green sheets includingone type of conductor pattern formed thereon in common, and by shiftingthe position of the conductor pattern between the A pattern and the Bpattern when the ceramic green sheets are laminated. Accordingly, themother laminate can be manufactured by using the ceramic green sheetsincluding the one type of conductive pattern formed thereon.

In the other of the laminates adjacent to each other in the lengthwisedirection of the laminate when the mother laminate is divided asdescribed later, the ceramic green sheets including the conductorpatterns formed to be included in the first arrangement and becoming thefirst conductor layers 141 are each provided by the sheet of theabove-mentioned B pattern, and the ceramic green sheets including theconductor patterns formed to be included in the second arrangement andbecoming the second conductor layers 142 are each provided by the sheetof the above-mentioned A pattern. Thus, in each of the laminatesadjacent to each other in the lengthwise direction of the laminate whenthe mother laminate is divided as described later, the conductorpatterns included in the first arrangement and the conductor patternsincluded in the second arrangement are laminated with the dielectriclayer sandwiched between them in the laminating step (step S4).

Then, the mother laminate is divided (step S7). More specifically, themother laminate is divided along cut lines C₁ in the regions B and theregions C by a push cutter or a dicing machine, such that a plurality ofsoft laminates each having a substantially rectangular parallelepipedshape is obtained. Then, the soft laminates are subjected as appropriateto barrel grinding (step S8), such that outer surfaces (particularlycorners and ridges) of the soft laminates are rounded into curvedsurfaces.

Then, the soft laminates are fired (step S9). More specifically, thesoft laminates are heated to a predetermined temperature, such that theceramic materials and the conductive materials are sintered. As aresult, the laminates 110 are formed.

Then, the outer electrodes are formed (step S10). More specifically,conductive pastes to form the outer electrodes are coated over both theend portions of the laminate 110 by one of various printing methods, adipping method, etc., and are heated to form the underlying layers.

Then, the plating layers are formed on the underlying layers bydepositing metal components with a plating method. Through the step offorming the underlying layer and the step of forming the plating layer,the outer electrodes 120 can be provided over the both end portions ofthe laminate 110 such that the outer electrodes 120 are electricallyconnected to the conductor layers 140. The multilayer capacitor 100according to this preferred embodiment can be manufactured through aseries of the above-described steps.

In each of the outer electrodes in the ultra-small multilayer capacitor,the underlying layer preferably has a smaller thickness, for example, byforming it by a sputtering method instead of coating the conductivepaste. It is to be noted that the underlying layer is not alwaysrequired to be formed. With omission of the underlying layer, thethickness of the outer electrode is reduced, and the volume of thelaminate is increased without increasing the size of the multilayercapacitor 100. With an increase in the volume of the laminate, thenumber of the ineffective dielectric layers is able to be increased, andthe degree of freedom in design to obtain the desired electrostaticcapacitance is able to be increased.

An experimental example aiming to clarify a relation of the number ofthe laminated ineffective dielectric layers and the (total) number ofthe laminated conductor layers with respect to the electrostaticcapacitance of the multilayer capacitor will be described below.

Experimental Example

In an experimental example, three types of samples each including theeffective dielectric layers laminated in the same number, i.e., 21, andincluding the ineffective dielectric layers laminated in differentnumbers were prepared. More specifically, the number of the laminatedineffective dielectric layers was 0 in the sample 1, 10 in the sample 2,and 22 in the sample 3. In other words, the (total) number of thelaminated conductor layers was 22 in the sample 1, 32 in the sample 2,and in the sample 3. The total thickness of the first outer layerportion 131 and the second outer layer portion 132 is reduced by anamount corresponding to an increase in the number of the laminatedineffective dielectric layers. Thus, the total thickness of the firstouter layer portion 131 and the second outer layer portion 132 isreduced in the order of the sample 1, the sample 2, and the sample 3.

Conditions in common to the three types of samples were as follows. Theexternal dimensions (design values) of the laminate (after firing) were0.212 mm in length, 0.102 mm in width, and 0.102 mm in thickness. Thedimensions (design values) of the conductor layer (after firing) were0.122 mm in length, 0.047 mm in width, and 0.65 μm in thickness. Thedimension (design value) of the dielectric layer (after firing) was 0.75μm in thickness. The number of the laminated dielectric layers was 21.

The electrostatic capacitance of the multilayer capacitor was measuredby employing an electrostatic capacitance meter (LCR meter) under themeasurement conditions in conformity with the standard specification(JIS C 5101-11998).

The extent of curvature of the conductor layer in the sectionperpendicular or substantially perpendicular to the lengthwise directionL of the laminate 110 was determined by making a WT section passingthrough the center of the laminate 110 that had been exposed bypolishing, observing the exposed section with a scanning electronmicroscope or an optical microscope, measuring the extent B₁ ofcurvature of the conductor layer 140 closest to the first principalsurface 111 in the lamination direction of the laminate 110 and theextent B₂ of curvature of the conductor layer 140 closest to the secondprincipal surface 112 in the lamination direction of the laminate 110,and by adopting larger one of the measured values.

The extents B₁ and B₂ of curvature of the conductor layers 140 were eachdetermined as a value obtained by measuring, along the thicknessdirection T of the laminate 110, a distance between the center and theend portion of the relevant conductor layer 140 in the widthwisedirection W of the laminate 110. The thickness of the dielectric layerwas determined as a value obtained by observing the WT section passingthrough the center of the laminate 110 with a scanning electronmicroscope or an optical microscope, and by measuring the thickness ofthe dielectric layer along a linear line passing through the center ofthe laminate 110.

The effective width of the conductor layer was determined by making theWT section passing through the center of the laminate 110 exposed bypolishing, observing the exposed section with a scanning electronmicroscope or an optical microscope, measuring, for each of theeffective dielectric layer closest to the center of the laminate and theeffective dielectric layers positioned at both the ends of the laminatein the lamination direction, a width of a portions in which theconductor layers sandwiching each of those three effective dielectriclayers are opposed to each other, and by adopting an average value ofthe widths measured for those three effective dielectric layers.

The effective length of the conductor layer was determined by making anLT section passing through the center of the laminate 110 exposed bypolishing, observing the exposed section with a scanning electronmicroscope or an optical microscope, measuring, for each of theeffective dielectric layer closest to the center of the laminate and theeffective dielectric layers positioned at both the ends of the laminatein the lamination direction, a length of the portion in which theconductor layers sandwiching one of those three effective dielectriclayers are opposed to each other, and by adopting an average value ofthe lengths measured for those three effective dielectric layers. Theapparent effective area of the conductor layer was determined as theproduct of the effective width of the conductor layer and the effectivelength of the conductor layer.

The Table below lists the results obtained in the experimental example.FIG. 11 is a graph depicting a relation between the number of thelaminated ineffective dielectric layers and the electrostaticcapacitance of the multilayer capacitor. FIG. 12 is a graph depicting arelation between the number of the laminated ineffective dielectriclayers and the apparent effective area of the conductor layer. In FIG.11, the vertical axis represents the electrostatic capacitance (nF) ofthe multilayer capacitor, and the horizontal axis represents the numberof the laminated ineffective dielectric layers. In FIG. 12, the verticalaxis represents the apparent effective area (mm²) of the conductorlayer, and the horizontal axis represents the number of the laminatedineffective dielectric layers.

TABLE Number of Number of Apparent laminated laminated Number ofEffective Effective effective Extent of Electrostatic effectiveineffective laminated width of length of area of curvature ofcapacitance dielectric dielectric conductor conductor conductorconductor conductor (nF) of layers layers layers layer layer layer layermultilayer (total) (total) (total) (mm) (mm) (mm²) (μm) capacitor Sample1 21 0 22 0.0471 0.1222 0.00574 5.47 4.55 Sample 2 21 10 32 0.04910.1230 0.00604 5.93 5.22 Sample 3 21 22 44 0.0519 0.1226 0.00636 6.425.90

As seen from the Table and FIG. 11, the electrostatic capacitance of themultilayer capacitor increases in proportion to the number of thelaminated ineffective dielectric layers. Furthermore, as seen from Tableand FIG. 12, the apparent effective area of the conductor layerincreases in proportion to the number of the laminated ineffectivedielectric layers.

As a result of reviewing the above-mentioned results of the experimentalexample in detail, the inventors have discovered the following.

The reason why the apparent effective area of the conductor layerincreases in proportion to the number of the laminated ineffectivedielectric layers resides in that the number of void portions where thedielectric portion 13 does not exit is increased in the regions B and Cof the mother laminate 11, as illustrated in FIGS. 7 and 8, byincreasing the number of the laminated ineffective dielectric layers,namely by increasing the (total) number of the laminated conductorlayers. When the pressure bonding is performed on the mother laminate,the conductor patterns 14 are pressed and stretched to come into thevoid portions. As a result, the conductor layers are expanded outwardsas illustrated in FIGS. 4 and 5, and the apparent effective area of eachof the conductor layers is increased.

As seen from the Table, in the sample 2, the apparent effective area ofthe conductor layer increases about 5.2% and the electrostaticcapacitance of the multilayer capacitor increases about 14.7% incomparison with those in the sample 1. In the sample 3, the apparenteffective area of the conductor layer increases about 10.8% and theelectrostatic capacitance of the multilayer capacitor increases about29.7% in comparison with those in the sample 1.

Thus, an increase rate of the electrostatic capacitance of themultilayer capacitor is larger than that of the apparent effective areaof the conductor layer. The reason is presumably resides in theinfluence resulting from the extent of curvature of the conductor layer.

The reason why the extent of curvature of the conductor layer increasesin proportion to the number of the laminated ineffective dielectriclayers increases is as follows. As discussed above, the number of thevoid portions where the dielectric portion 13 does not exit is increasedin the regions B and C of the mother laminate 11, as illustrated inFIGS. 7 and 8, by increasing the number of the laminated ineffectivedielectric layers, namely by increasing the (total) number of thelaminated conductor layers. In other words, the density of the laminatedconductor patterns is reduced in the regions B and C. Therefore, whenthe pressure bonding is performed on the mother laminate, the extent ofcurvature of the mother sheets positioned in the regions B and C of themother laminate 11 is increased as illustrated in FIGS. 9 and 10. Thus,the extent of curvature of the conductor layer increases as the numberof the laminated ineffective dielectric layers increases.

With the curving of the conductor layers sandwiching the effectivedielectric layer between them, the area in which the conductor layersare opposed to each other is further increased. While theabove-described apparent effective area of the conductor layer is thearea in which the conductor layers are opposed to each other when lookedat in a plan view, the effective area actually contributing to theelectrostatic capacitance, in which area the conductor layers areopposed to each other, is increased because of the conductor layersbeing curved.

The inventors have discovered that the electrostatic capacitance of themultilayer capacitor is able to be increased by increasing the number ofthe laminated ineffective dielectric layers, thus increasing theeffective area actually contributing to the electrostatic capacitance,in which area the conductor layers are opposed to each other.Furthermore, the inventors have clarified that the electrostaticcapacitance of the multilayer capacitor increases in proportion to thenumber of the laminated ineffective dielectric layers. In other words,the inventors have clarified that the electrostatic capacitance of themultilayer capacitor is able to be finely adjusted by increasing thenumber of the laminated ineffective dielectric layers, therebyincreasing the (total) number of the laminated conductor layers, withoutchanging the number of the laminated effective dielectric layers.

In this experimental example, the increase rate of the electrostaticcapacitance per ineffective dielectric layer is 29.7%÷22=1.4%. Theincrease rate of the electrostatic capacitance per effective dielectriclayer is 1÷21×100=4.8%.

An ultra-small multilayer capacitor having the desired electrostaticcapacitance can be obtained by utilizing the above-described mechanism.FIG. 13 is a flowchart representing a non-limiting example of amanufacturing method for the multilayer capacitor according to the firstpreferred embodiment of the present invention.

As illustrated in FIG. 13, the manufacturing method for the multilayercapacitor according to the first preferred embodiment of the presentinvention includes a design step (step S11) of determining the totalnumber of the effective dielectric layers and the total number of theconductor layers on the basis of the electrostatic capacitance pereffective dielectric layer and the increase rate of the electrostaticcapacitance of the multilayer capacitor resulting from an increase ofone ineffective dielectric layer, the former electrostatic capacitanceper effective dielectric layer and the latter increase rate of theelectrostatic capacitance being calculated from three parameters, i.e.,the dielectric constant of the dielectric constituting the dielectriclayer, the area of the first conductor layer and the second conductorlayer opposing to each other, and the distance between the firstconductor layer and the second conductor layer opposing to each other.The manufacturing method further includes a step (S12) of manufacturingthe multilayer capacitor in accordance with the determination in thedesign step. Thus, in the step (S12) of manufacturing the multilayercapacitor, the conductor layers and the dielectric layers are laminatedin respective numbers on conditions of satisfying the total number ofthe effective dielectric layers and the total number of the conductorlayers, which have been determined in the design step (step S11).

More specifically, after confirming the increase rate of theelectrostatic capacitance per ineffective dielectric layer, the (total)number of the laminated effective dielectric layers to ensure theelectrostatic capacitance in units of about 5% and the (total) number ofthe conductor layers to ensure the electrostatic capacitance in units ofabout 1.5% are determined in the design step (step S11).

By manufacturing the multilayer capacitor in accordance with theabove-described determination in the design step, the desiredelectrostatic capacitance is able to be ensured in the ultra-smallmultilayer capacitor in which the (total) number of the laminatedconductor layers is small.

The increase rate of the electrostatic capacitance per ineffectivedielectric layer is able to be adjusted by changing respective amountsof binders contained in the ceramic slurry and the conductive paste,thus changing easiness in stretching the ceramic green sheets and theconductor patterns.

In order to adjust the electrostatic capacitance of the multilayercapacitor by increasing or decreasing the number of the laminatedineffective dielectric layers, it is required to stretch the conductorpatterns in the above-described stretching step (step S5), and to curvethe conductor patterns, which become the conductor layers, in theabove-described bending step (step S6). As a result of conductingintensive studies, the inventors have discovered that the conductorpatterns are able to be each effectively stretched and curved bysetting, in the multilayer capacitor, the width of the conductor layer140 to satisfy conditions that the difference between the width of theconductor layer 140 and the width of the laminate 110 is less than about0.12 mm, and that the width of the conductor layer 140 is about 70% orless of the width of the laminate 110, for example.

In more detail, if the region C is too narrow in FIG. 8, the conductorpatterns are less susceptible to stretching when they are pressed. Fromthat point of view, the width of the conductor layer 140 is preferablyabout 70% or less of the width of the laminate 110 to ensure that theconductor patterns are sufficiently pressed and stretched. To thecontrary, if the region C is too wide, the ceramic green sheets arepressure-bonded to each other in a way of filling the void portions inthe region C before the conductor patterns are sufficiently pressed andstretched. Hence the conductor patterns are less susceptible tostretching when they are pressed. From that point of view, thedifference between the width of the conductor layer 140 and the width ofthe laminate 110 is preferably less than about 0.12 mm to ensure thatthe conductor patterns are sufficiently pressed and stretched. With theconductor patterns being sufficiently pressed and stretched, theconductor patterns are able to be sufficiently curved by the ceramicgreen sheets having flowed into the region C.

As in the multilayer capacitor according to the first preferredembodiment of the present invention, the extent of curvature of at leastone of two conductor layers 140 in the section perpendicular orsubstantially perpendicular to the lengthwise direction L of thelaminate 110, those two conductor layers 140 being positioned at boththe ends of the laminate 110 in the lamination direction, is preferablylarger than the thickness of the ineffective dielectric layer that isadjacent to the relevant conductor layer 140, in order to reliablyensure the effective area actually contributing to the electrostaticcapacitance, in which area the conductor layers are opposed to eachother.

Furthermore, in the design step (step S11), the layout of theineffective dielectric layer is preferably determined such that at leastone of the two conductor layers 140 positioned at both ends of thelaminate 110 in the lamination direction is adjacent to the ineffectivedielectric layer. In such a case, the reliability of the multilayercapacitor 100 is increased because the ineffective dielectric layerpositioned at the end of the laminate 110 in the lamination directionexhibits the function of protecting the effective dielectric layers thatare positioned inside the inner layer portion.

Moreover, in the design step (step S11), the layout of the ineffectivedielectric layer is preferably determined such that the conductor layer140 positioned at the center of the laminate 110 in the laminationdirection is adjacent to the ineffective dielectric layer. In such acase, because the dielectric layer positioned at the center of thelaminate 110 where the mother sheet is likely to be most thinned by thepressure-bonding of the mother sheets is given as the ineffectivedielectric layer, there is no possibility of short-circuiting even whenthe ineffective dielectric layer is thinned and insulation resistance isreduced. As a result, the reliability of the multilayer capacitor 100 isincreased.

A multilayer capacitor and a manufacturing method for the multilayercapacitor, according to a second preferred embodiment of the presentinvention, will be described below. The multilayer capacitor and themanufacturing method for the multilayer capacitor, according to thesecond preferred embodiment, are different from the multilayer capacitorand the manufacturing method for the multilayer capacitor, according tothe first preferred embodiment, only in lamination pattern of thelaminate. Therefore, description of the other points is not repeatedhere.

Second Preferred Embodiment

FIG. 14 is a sectional view illustrating a structure of the multilayercapacitor according to the second preferred embodiment of the presentinvention. A section illustrated in FIG. 14 is taken in the same manneras that illustrated FIG. 2. A section of the multilayer capacitorillustrated in FIG. 14, taken along a line III-III and viewed from adirection denoted by arrow, is as per illustrated in FIG. 3.

As illustrated in FIG. 14, the multilayer capacitor 200 according to thesecond preferred embodiment of the present invention includes thirdconductor layers 240 that are disposed in spaced relation from the endportions of the first conductor layers 141 at the side closer to thesecond end surface 116, and that are connected to the second outerelectrode 122. The multilayer capacitor 200 further includes fourthconductor layers 241 that are disposed in spaced relation from the endportions of the second conductor layers 142 at the side closer to thefirst end surface 115, and that are connected to the first outerelectrode 121.

In the manufacturing method for the multilayer capacitor according tothe second preferred embodiment of the present invention, pressurebonding is performed on the mother laminate as follows.

FIG. 15 is a sectional view of the multilayer capacitor according to thesecond preferred embodiment of the present invention, taken along alengthwise direction L thereof, the view illustrating the motherlaminate before being pressed. FIG. 16 is a sectional view of themultilayer capacitor according to the second preferred embodiment of thepresent invention, taken along the lengthwise direction L thereof, theview illustrating the mother laminate after being pressed. A section ofthe multilayer capacitor taken along a widthwise direction W thereof issimilar to that of the mother laminate in the first preferredembodiment. Therefore, description of that section is not repeated here.

As illustrated in FIG. 15, in a mother laminate 21, regions A₁ and A₂where the conductor patterns 14 exist in a comparatively large numberand regions B₁ and B₂ where the conductor patterns 14 exist in acomparatively small number are repeatedly arrayed in the order of A₁,B₁, A₂ and B₂ in the lengthwise direction L of the mother laminate 21.

As illustrated in FIG. 15, the mother laminate 21 is pressed in thelamination direction for pressure bonding with a pair of flat-plate dies91 by employing an isostatic press, for example, the pair of flat-platedies 91 including rubbers 92 that are attached to their pressingsurfaces. In the mother laminate 21, the density of the laminatedconductor patterns is higher in the regions A₁ and A₂ than in theregions B₁ and B₂. Upon being pressed against the mother laminate 21,therefore, the rubbers 92 are caused to flow and deform from the regionsA₁ and A₂ toward the regions B₁ and B₂, thus projecting in a downward orupward convex shape, as illustrated in FIG. 16. Hence the mother sheetspositioned in the regions B₁ and B₂ of the mother laminate arepressure-bonded to each other while being subjected to drawing such thatthe mother sheets come into a close contact state. As a result, themother laminate is formed.

Thereafter, the mother laminate is divided (step S7). More specifically,the mother laminate is divided along cut lines C₂ in the region A₂ by apush cutter or a dicing machine, such that a plurality of soft laminateseach having a substantially rectangular parallelepiped shape isobtained.

In this preferred embodiment, the effective area of the conductor layercan be adjusted by changing, in the lengthwise direction L of themultilayer capacitor 200, the positions at which the ceramic greensheets the A pattern and the B pattern, each including the conductorpattern formed thereon, are laminated. With the manufacturing method forthe multilayer capacitor according to this preferred embodiment, thedesired electrostatic capacitance can also be ensured in the ultra-smallmultilayer capacitor in which the (total) number of the conductor layersis small.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A multilayer capacitor comprising: a laminateincluding conductor layers and dielectric layers alternately laminated,the laminate including external dimensions including a length of about0.45 mm or less and a width of 0.25 mm or less when viewed from alamination direction; and a first outer electrode and a second outerelectrode disposed on surfaces of the laminate, which are spaced fromeach other in a lengthwise direction of the laminate; wherein in thelaminate, the dielectric layers and the conductor layers are alternatelylaminated such that the conductor layers are in a first arrangement anda second arrangement, the second arrangement being different from thefirst arrangement when viewed from the lamination direction, and suchthat the conductor layers are included in the first arrangement or thesecond arrangement; the first outer electrode is connected to ones ofthe conductor layers included in the first arrangement; the second outerelectrode is connected to others of the conductor layers included in thesecond arrangement; a width of each of the conductor layers has adifference of less than about 0.12 mm between a width of the conductorlayer and a width of the laminate, and is about 70% or less of the widthof the laminate; at least one of the dielectric layers is an ineffectivedielectric layer that is sandwiched between the conductor layers bothincluded in one of the first arrangement and the second arrangement; atleast one of the dielectric layers is an effective dielectric layer thatis sandwiched between the conductor layer included in the firstarrangement and the conductor layer included in the second arrangement;at least one of the conductor layers adjacent to the effectivedielectric layer is curved in the lamination direction; and each of aplurality of the conductor layers has an arc shape in which a thicknessof a central portion of the conductor layer in a widthwise direction ofthe laminate is greater than a thickness of an end portion of theconductor layer in the widthwise direction.
 2. The multilayer capacitoraccording to claim 1, wherein at least one of the two conductor layerspositioned at both ends of the laminate in the lamination direction isadjacent to the ineffective dielectric layer.
 3. The multilayercapacitor according to claim 1, wherein external dimensions of themultilayer capacitor are about 0.212 mm or less in length and about0.102 mm or less in width when viewed from the lamination direction.